Although I wouldn’t dream of doing it unless forced at knife-point (or
threatened with suspension of my beer allowance), you can also
convince grub to boot windows–against its better judgement.

Installation

If I really had any clue, I would have made careful notes as this
sytem came together, so I could reproduce exactly what I
did. Sigh. Anyhow, it started off with just the smaller hard disk
(/dev/hda) containing a single install of Debian. When I got the
groovy new 60Ger and decided to go nuts, I installed Debian Woody on
that, and allocated a decent chunk to my /home filesystem. I then
proceeded to carve up the original disk for various BSDs and Hurds.

A reasonable amount of research in the web before I started convinced
me that it would all end in disaster, and my four year old debian sid
install that started life as potato would be toast… but what the eh,
it’s all in the name of science. As it turned out, it was far less
traumatic than I thought–my biggest heart ache was discovering the
particular mysterious incantations that grub needed for each OS.

It’s probably important that the *BSDs live in primary
partitions–this will somewhat limit your flexibility in having six
thousand OSes on a single disk. Linux is not so particular, and hurd
would probably happily live in that little mat of fluff that gathers
in the cooling vents of your PC.